plot_utils.py

import matplotlib.colors as mc
import colorsys

def lighten_boxplot(ax):
    
    # https://stackoverflow.com/questions/55656683/change-seaborn-boxplot-line-rainbow-color
    def lighten_color(color, amount=0.5):  
        # --------------------- SOURCE: @IanHincks ---------------------
        try:
            c = mc.cnames[color]
        except:
            c = color
        c = colorsys.rgb_to_hls(*mc.to_rgb(c))
        return colorsys.hls_to_rgb(c[0], 1 - amount * (1 - c[1]), c[2])

    for i,artist in enumerate(ax.artists):
        # Set the linecolor on the artist to the facecolor, and set the facecolor to None
        col = lighten_color(artist.get_facecolor(), 1.2)
        artist.set_edgecolor(col)    

        # Each box has 6 associated Line2D objects (to make the whiskers, fliers, etc.)
        # Loop over them here, and use the same colour as above
        for j in range(i*6,i*6+6):
            line = ax.lines[j]
            line.set_color(col)
            line.set_mfc(col)
            line.set_mec(col)